As a medical instrument used for a treatment in the event of narrowing of blood vessel, a tubular metallic member in meshwork form called a stent is known. This stent is held in a narrowing portion of a blood vessel for a long period of time to continuously extend the narrowing portion. In doing an endurance test on the stent, therefore, it is important to consider the state in which the stent is held in a blood vessel. However, it is impossible to actually do such an endurance test in a human body and there is a need to do such a test with a mechanical apparatus simulating features of a human body.
As an apparatus for evaluating the performance of stents, a stent performance evaluation simulator disclosed in Patent Document 1 and a stent mechanical characteristic measuring apparatus disclosed in Patent Document 2 are known.
The stent performance evaluation simulator according to Patent Document 1 has a circuit configuration simulating coronary circulation and is provided with a fluid path in closed loop form, a pump for producing a pulsating flow in a fluid circulating through the fluid path, a branch line branching at an intermediate position in the fluid path, and a flexible tube provided at an intermediate position in the branch line. A stent to be evaluated is held in the flexible tube and is subjected to the fluid in which the pulsating flow is produced. With this simulator, therefore, the endurance of the stent can be examined under conditions close to the blood pulsating conditions in actual use of the stent.
The stent mechanical characteristic measuring apparatus according to Patent Document 2 is an apparatus which directly pulls a stent from one end side of the same to derive a correlation between a load acting on the stent and the stretched length, whereby the performance of the stent is evaluated from a mechanical point of view.
In a case where a stent is held in a superficial femoral artery (SFA) in a femur of a human body, the vessel moves more largely than other portions and a large load can act easily on the stent held in the vessel, because the superficial femoral artery is a vessel having dynamic factors. In a case where a stent is held in a superficial femoral artery, therefore, it can damage more easily with time than in other portions. More specifically, biomechanical loads, such as torsion, contraction or extension, act on the superficial femoral artery, for example, as a result of an external force due to a motion or the like of a leg portion and a change in blood pressure, and the stent use environment is worse than in other vessel portions. From the stent held in the superficial femoral artery differing as a user environment from other portions, therefore, a result of an endurance test different from the result of actual use is produced to reduce the reliability of the endurance test, unless the endurance test is conducted by considering the above-described biomechanical loads.
Each of the simulator according to the above-mentioned Patent Document 1 and the apparatus according to the above-mentioned Patent Document 2, however, is incapable of simulating the behavior of a blood vessel resulting from the above-described biomechanical loads specific to the superficial femoral artery and correctly evaluating the endurance of a stent held in the superficial femoral artery.
With respect to a coronary artery stent held in the coronary artery, an instance of damage in a state of being held in a patient has also been reported. There is a demand for a system capable of predicting the endurance in an environment in which the above-described biomechanical loads are simulated.
Further, when a doctor or a medical student goes into anastomosis procedure training by inosculating an artificial blood vessel for training already put on the market, no apparatus exists with which the endurance of an inosculated portion of the obtained inosculated artificial blood vessel is tested by causing the artificial blood vessel to behave in the same way as in the actual postoperative state of a patient, and it is impossible to make an objective evaluation of the anastomosis procedure by considering the behavior of the blood vessel.    Patent document 1: Japanese Patent Publication No. 2000-342692    Patent document 2: Japanese Patent Publication No. 2005-278828